Atlantic Beds advertises that they deliver the memory foam mattress flat in a box and not compressed and rolled. Is that a major difference - does it affect the longevity of the mattress? Is it worth the extra $300 to a what seems to be comparable from Christeli?
If a mattress is compression packed for only a short time (a few weeks or less) or only compressed just before shipping it shouldn’t have an effect on durability as long as the foam is suitable for compression (not too firm or stiff).
If it’s compressed for longer periods of time (such as longer shipping times from offshore or storage in a warehouse) then it can affect durability.
Shipping a mattress with common carrier can add to the final cost of a mattress compared to shipping with courier so if the mattresses were exactly the same and if the materials were suitable for compression then it probably wouldn’t justify an extra cost but they aren’t exactly the same and there will also be other differences between two mattresses that can affect the “value” of a mattress purchase or the price you pay. I would compare them based on the final cost to you and taking into account all the other parts of your personal value equation that are most important to you.
Their descriptions appear to be similar to the Christeli mattresses so if I had to guess is would say they are a re-seller for mattresses made by Park Place but I don’t know that for certain.